Physics Flashcards
When was the big bang
13.8 billion
When does red-shift happen
When a source is moving away
When does blue shift happen
When a source is moving towards
How do we know our sun contains helium
There are black lines in the spectrum of the light from the Sun where helium has absorbed light
How do we know the universe is moving away from a single point
Light spectra from edge of universe shows red shift
What shift has light from most galaxies been observed to have
Red shift
Which galaxies are moving the fastest
Furthest galaxies
What evidence that universe is expanding
The furthest galaxies move fastest
What shows the universe was once very small
It’s stil expanding
What are galaxies held together by
Gravity
What can stop the expansion of the universe
Gravity between galaxies
What can the presence of dark matter mean
The average density of the universe would be much bigger
How much dark energy is universe made up of
68%
How much of the universe is dark matter made up of
27%
What takes up the remaining 5% of universe
Normal matter
2 main types of telescope
Refracting telescope - lense refract and focus the light
Reflecting telescope - curved mirrors reflect and focus the light
Problems with refracting telescope
Faint Image - some light reflects off the lens
Large lens needed to improve magnification - can be difficult to do
How does reflecting telescope work
Image formed by reflection from a curved mirror
Then magnified by secondary mirror
When/where first telescope invented
Netherlands - 17th century
Optical telescope
observe visible light from space
Optical telescope on the ground
Can only be used at night
Can’t be used if cloudy weather
Radio telescopes
detect radio waves coming from space - can be used in bad weather as radio waves not blocked by clouds
Earth orbiting telescope designed for
designed to relay astronomical data to the earth
Space telescopes
Telescopes in space observe whole sky
Why is moon considered a satellite
Moves around Earth (orbits planet)
Do planets emit visible light
No
What makes a satellite successfully orbit Earth
When its speed is balanced by the pull of Earth’ gravity
Which satellite takes longest to orbit Earth
Moon
Alternative to big bang theory
Steady state
Steady state theory
Universe always existed without a beginning of time
2 main theories
Universe has always existed
Began from a small region
What is a theory
An attempt to explain phenomena in our universe
What happened 300,000 years after the big bang
Temperature dropped enough for atoms to form
When was milky way formed
After billions of years galaxies start to form
5 billion years ago
8.7 billion years after the big bang
Doppler effect
Source of waves
Wavelength and frequency remain constant
What happens the faster a light souce moves
The further its light will be shifted and the further away it is
Cosmic Microwave Background Radiation
CMBR
The remains of energy created after Big Bang
Which direction does CMBR come from
Every direction
What depends on galaxies to stop expansion of universe
Mass of galaxies
How much space is between them
How much space they take up
Density
What happened first 3 min after big bang
Protons neutrons formed but it was too hot for atoms to form
When did universe cool for atoms to form
380,000 years after big bang
300-400 million years after big bang
Earliest stars began to form
When did humans first start to form
Between 5 - 7 million years ago
1 way big bang supported by evidence
Cosmic microwave background radiation
Light year
Distance measured in space - distance light travels in 1 year
How far is a lightyear
M km
186,000 miles
Per second
300,000 km
Forces that act on a rocket as it takes off
Gravity
Drag force
Forces that keep satellite in orbit
Gravity
Air resistence
Drag
How to get satellites in orbit
Launching a satellite in orbit by attaching it to a rocket
Which part of the Earth do satellites pass over
Geostationary orbit
Low polar orbit
Low earth orbit
Geostationary - above equator
Low polar - north pole south pole
Low earth - below 1000km from earth
How long do satellites take to complete 1 orbit
Geostationary
Low polar
Low earth
Geostationary - a day
Low polar - 90-120 min
Low earth - 90-120 min
Do Geostationary, low polar, lower earth, satellite stay over same place
G - yes
LPO | LEO - no
Which satellite checks on cyclones hurricanes and why
Geostationary and low earth orbit
G - provide continuous monitoring of the Earth’s surface
Wat satellite checks on climate change
Low earth orbit
Satellite takes 24 hours orbit earth radius is 42,000km
42,000 ➗ 24
How to calculate a speed of satellite
Speed = distance ➗ time
ISS travels 42,725 how calculate radius of orbit
2 x 3.14 x 42725
State 1 similarity and 1 difference between refraction reflective telescope
Refraction uses lens and reflective uses a curved mirror
both telescopes make a small, inverted image of whatever it’s pointed at
How do scientists investigate universe
Use telescopes to different parts of electromagnetic spectrum to study objects in space
Why hubble telescope uses mirrors not lenses
To help astronomers see far away objects in space more clearly
Advantages reflecting telescope
Large apertures, no chromatic aberrations, excellent price value ratio
Advantages refracting telescope
Advantages - low maintanence, portability, sharp bright images
Describe the orbit of an artificial satellite
These orbits are much higher than polar orbits so satellites travel more slowly
A table - average distance - 391,400, 42,200, 26000
Time taken - 28 days, 1 day, 12 hour, 3.8 hours
What conclusion
As average distance decreases average speed increases
3 radiations
Alpha beta gamma
Alpha - emission of an alpha particle
Beta - emission of electrons or positrons
Gamma - emission of energetic photons
1st living things to go to space
Fruit flies
Inflation theory
At the beginning of the universe expanded faster than the speed of light
Disadvantages refraction telescope
Expensive
Limited aperture
Chromatic aberration
Disadvantage reflection telescopes
Lack of poratbility
Lower contrast
Higher maintanence requirements
Describe the action and purpose of a solar panel
convert sunlight into electrical energy
